Thixotropic heterogeneous monopropellant compositions



No Drawing.

- with decreasing stress.

. 3 its 8% Tnixornorro r nrnnoonnnoos MoNo- PROPELLANT cos irosrrronsJoe-M. Burton, Alexandria, Va, assignor to Atlantic- ResearchCorporation, Alexandria, Va, a corporation of Virginia 1 f Filed June27, 1962, tier. No. M95564 27 Claims. (Cl. 149-49) This inventionrelates to new heterogeneous monopropellant compositions capable ofgenerating gases containing high available energy for such purposes asproducing thrust or power, heat energy or gas pressure. Morespebifically, it relates to plastic, extiudable, shape-retainingmonopropellant compositions of. high density comprising a finely-dividedsolid oxidizer dispersed in a continuous inatrixof a viscous liquidfuel. This application is a continuation-in-part of application SN.791,486 to Joe M.

Burton, filed February 5, 1959, now abandoned.

'Ihe term monopropellant refers to a composition which is substantiallyself-sufficient 'with regard to its oxidant requirements asdistinguished firom biprropel'lants where until admixture at the pointof combustion. The term heterogeneous refers to the two-phase solidoxidizerj liquid matrix system.

nates many of their disadvantages. Such semi-solid monopropellants aredisclosed in cmpending Scurlock application SN. 694,897, filed November6, 1957, now Patent No. 3,095,334, issued June 25, 1963. I

For uniform burning of such plastic, heterogeneous f mono-propellants,it is essential that the solid oxidizer and any other solid component,such as a finely-divided metal fuel, remain uniformly and stablydispersed. It is also desirable that the composition be thixotropic,namely, tend, above a certain minimum stress, to increase in fluiditywith increasing stress and to decrease in fluidity- To obtain thedesired phase-stability and thixotropy, it has generally been necessaryto dissolve ,a gelling agent in the liquid matrix. This has thepractical disadvantage of requiringan additional gelling step,frequently With concomitant heating for solu- 'tion. of the gellingagent. Syneresis" and irreversible destruction-of the gel structureunder conditions, such as' freezing, also limit the range of usefulnessof many of the gelled compositions.

is to provide stable, high e objectof this invention density,heterogeneous, extrudable monopropellant cornpositions comprisingfinely-divided solid oxidizer disa combustion chamber wherethey areburned to generate high energy gases for developing thrust or power orfor providing heat or gas pressure.

Another object is to provide such heterogeneous com' positions whichpossess the requisite plasticity, cohesiveness, tensile strength, andfreedom from phase separa- Other objects and advantages'will becomeobvious from the following detailed description.

tion without'requiring the addition of a gelling agent.

United States Patent v the fuel is maintained separately from theoxidizer source 2 finely-divided solid oxidizer and other solidcomponents, such as a finely-divided metal fuel, in stable, uniformdipersion without separation for indefinitely long periods of time andwill, furthermore, impart excellent thixotropic properties to theplastic propellant mixture without requiring the addition of a gellingagent.

My new monopropellant compositions accbndingly comprise stabledispersions of finely-divided,insoluble, solid oxidizer in a continuous,non-volatile,- liquid fuel matrix comprising a viscous, liquid, organicpolymer which can be oxidized toform hot combustion gases. Thecompositions can also contain dispersed therein, a finely-divided metalas an additional fuel component. Admixturre with the liquid of adequateamounts of the finely-divided solids results in plastic,extrudablemonopropellant compositions of suiliciently high cohesivestrength to retain a formed shape while being capable of continuous flowat ordinary to reduced temperature.

The plastic compositions possess characteristics of non- Newtonianliquids, namely yield to flow only under a finite stress.

These high density, plastic monoptropellants are particularly adapted tobeing fed at ambient temperatures under pressure from a storage chamberinto a combustion chamber in the form of any desired continuous coherentshape, such as a column, strip, or the like, with combusr tion takingplace on the leading face of the advancing material. Such a plastic,two-phase system, in which the solid oxidizer is uniformly dispersed ina continuous liquid matrix, ensures smooth coherent flow and, veryimportantly, a constant mass burning rate for a given area of exposedburning surface. in this respect, the burning properties are similar tothose of a solid propellant grain.

The shape-retentive cohesiveness of the nionopro'pellant material shouldpreferably be sufficiently high so that it possesses a minimum tensilestrength of about 0.01 p.s.i. and preferably about 0.03 psi. or higher.The material shouldhowever, be capable of yielding to continuous flow atordinary to reduced temperatures under stress or pressure. The use ofexcessively high pressures to produce the requisite fiow is undesirablefor practical persed in a viscous liquid polymer for extrusion as cohosve, shape-retaining, continuously advancing'masses into I have foundthat a liquid fuel vehicle comprising, at

least in part, a viscous liquid organic polymer, and having a minimumviscosity of about 400 centipoises at 77 reasons, although availablepressure-producing devices will, of course, vary with particularapplications The maximum shear stress at a Wall, required to initiateand sustain how of the composition at ordinary orambient temperatures,is preferably not higher than about 1 p.s.i.

with a maximum of about 10 psi.

The physical properties of the extrudable, plastic mix, such ascohesiveness, tensile strength, pressure required to produce flow,- andstability of the two-phase system,

are largely determined' by such factors as the viscosity" l of theliquid fuel matrix and the concentration and particle size of the soliddisperse phase. The afore listed properties can be increased ordecreasedin degree by increasing or decreasing the viscosity of theliquid matrix, by increasing or decreasing the loading density of dis-ISince:

persed. solids, or by .a combination of both factors. the loadingdensity of the solids, namely the concentration of solid oxidizer oroxidizer and finely-divided metal I low viscosity (but at least about400 centipoises and'preferably at least 1500), is adequate to providethe requisite I F.,;p-re ferably a minimum of about 1500, will hold thestability against separation and the other essential physi calproperties. The lower viscosity of the liquid within the permissiblerange also facilitates mixing and uniform dispersion of the highconcentration of solids in the liquid vehicle. Where fuel-richpropellant compositions are desired for applications, such as gasturbines, requiring relatively low combustion temperatures, the amountof solid oxidizer can be reduced to the desired level while maintainingthe requisite dispersion stability, cohesiveness and other desiredphysical characteristics, by employing a liquid fuel matrix of highViscosity.

Any desired viscosity can be obtained by selecting a liquid polymerhaving the proper viscosity, by mixing the same or diiferent liquidpolymers of different viscosities in proper proportions, or by dilutinga liquid polymer of high viscosity with any miscible, substantiallynon-viscous, non-volatile liquid fuel, namely a liquid which burns toform hot combustion gases and has a viscosity less than the desiredviscosity of the liquid matrix as a whole. Thus the viscosity of such aliquid diluent can be substantially less than 400 centipoises.

The polymer forming the liquid matrix, in Whole or in part, can be anyorganic polymer which, though viscose, is sufliciently mobile to flow atordinary temperatures and which has a minimum viscosity at 77 F. ofabout 400 centipoi es, preferably about 1500. Such liquid polymers aregenerally of relatively low molecular Weight as compared with solidpolymers, the particular molecular Weight varying With the particularpolymer. The polymer is preferably one which does not further polymerizeduring storage with resulting increase in viscosity or solidification orone which can be stabilized against further polymerization by theaddition of a suitable inhibiting agent. Examples of suitable liquidpolymers for my purpose include the relatively low molecular Weightliquid hydrocarbon polymers, such as polyethylene, polypropylene,polyisobutylene, polyisoprene, and liquid rubber made by partial thermaldepolymerization of natural or synthetic rubber; the low molecularweight siloxanes, such as methyl siloxane, phenylsiloxane andmethylphenyl siloxane; liquid alkyd polyesters, such as the polyethyleneoxide or polypropylene oxide esters of a dibasic acid, such as adipic,sebacic, succinic, maleic, phthalic, terephthalic and isophthalic acid;liquid acrylic and methacrylic acid esters, such as polymethylmethacrylate; high molecular weight, viscose polydiols, such as thosemade from polyethylene oxide, polypropylene oxide, andpolytetrahydrofurane; liquid epoxy polymers; liquid phenolic polymers,such as polyphenol-formalde hyde; and many others.

The liquid polymer can be selected for its gas-generating andoxygen-demand properties in accordance With the specific requirementsfor the particular propellant use. In some cases, for example, it may bedesirable to employ a polymer, such as a polyester or siloxane, in whichthe combined oxygen, though not available for further oxidation, reducesthe stoichiometric oxidizer requirement for the molecule as a Whole.

As aforementioned, the viscosity of the liquid fuel matrix can betailored for any specific formulation by combining liquid polymers ofdifferent viscosity. The polymers can be chemically the same but ofdifferent molecular weight and, therefore, of difierent viscosity.Mixtures of chemically different liquid polymers of different viscosityare also entirely suitable.

In some cases, it may be expedient to dilute a highly viscous liquidpolymer with sufiicient non-volatile, substantially non-viscous,miscible liquid fuel to produce a liquid matrix of the particulardesired viscosity. This not only broadens the range of availablefuel-component formulations but also can be employed as a means forreducing the stockiness which is characteristic of some of the liquidpolymers.

The non-volatile, non-viscous, liquid fuel component can be an inertorganic compound, namely a compound which is combustible to producegaseous combustion products but which requires an external oxidizer foroxidation. It can, however, and often preferably does, contain combinedoxygen which is not available to any appreciable extent for furtheroxidation, such as oxygen which is linked to a C, Si, S, or P atom inthe molecule. Such inert liquid fuels have the advantage, important insome applications, of reducing stoichiometric oxygen requirements, and,where the oxygen is linked to carbon in the molecule, of reducing sootformation.

Examples of suitable inert, non-volatile, substantially non-viscous,organic liquid fuels include hydrocarbons, e.g., triethyl benzene,dodecane and the like; compounds containing some oxygen linked to acarbon atom, such as esters, e.g. dimethyl maleate, diethyl phthalate,dibutyl oxalate, dibutyl sebacate, dioctyl adipate, etc.; alcohols,e.g., benzyl alcohol, ethylene glycol, triethyene glycol, etc.; ethers,e.g., methyl ct-naphthyl ether; ketones, e.g., benzyl methyl ketone,phenyl o-tolyl ketone, isophorone; acids, e.g., Z-ethylhexoic acid,caproic acid, n-heptylic acid, etc.; aldehydes, e.g., cinnamaldehyde;nitrogen-containing organic compounds such as amines, e.g.,N-ethylaniline, tri-n-butylamine, diethyl aniline; nitriles, e.g.,caprinitrile; phosphorus-containing compounds, e.g., triethyl phosphate;sulfur-containing compounds, e.g., diethyl sulfate, and many others.These organic liquid fuels have viscosities which are substantially lessthan 406 centipoises at 77 F.

Non-volatile, substantially non-viscous liquid fuels, which areself-oxidant, namely contain combined oxygen or other element, such aschlorine or fluorine, available for oxidation of other components of themolecule, can also be employed as a viscosity-adjusting diluent alone orin combination with a non-viscous inert liquid fuel. Such an activeliquid component has the advantages of improving oxygen balance of thepropellant mixture and making stoichiometric oxygen levels more easilyobtainable, since it functions as a fluid vehicle for the solid oxidizerand, at the same time, reduces the total amount of solid oxidizerrequired for combustion of the reduced proportion of inert liquidpolymer or liquid polymer and non-viscous inert liquid fuel. The use ofan active, nonviscous, liquid diluent is particularly advantageous withinert liquids of high oxygen demand such as hydrocarbon polymers or withadded finely-divided metal fuels.

Examples of suitable, non-volatile, substantially nonviscous,self-oxidant liquids which have viscosities less than 400 centipoises at77 F. and which can be satisfactorily used include nitroglycerine,diethylene glycol dinitrate, pentaerithritol trinitrate, and1,2,4-butanetriol trinitrate. It should be noted that the inert liquidpolymer phlegmatizes these sensitive liquids so that the heterogeneousmonopropellant mixes containing such active liquid components are,nevertheless, suificiently insensitive to heat and shock.

The amount of substantially non-viscous liquid fuel component is notcritical and is determined by the viscosity of the liquid polymer andthe desired viscosity of the liquid fuel matrix. Where, for a particularapplication, a substantial amount of a particular non-viscous liquid,such as an oxygen-containing inert or active compound, is desired,excessive reduction of liquid matrix viscosity can be avoided by using aliquid polymer of sufficiently high viscosity to raise the viscosity ofthe liquid mixture to the desired level.

It is essential that the liquid fuel be non-volatile to ensure extendedshelf-life and storageability even at relatively high environmentaltemperatures Without loss of the liquid component by vaporization. Thisis necessary not only to maintain the predesigned combustioncharacteristics of the monopropellant but also to retain its desiredphysical characteristics. vaporization of sufficient liquid fuel toleave a solid, granular mass would make the monopropellant unfit for thedesired mode of use. The liquid polymers are, as a class, characterizedby the requisite non-volatility, so that discretion on this point mustbe exercised only with regard to the non-viscous liquid diluent, ifused. Maximum vapor pressure of such Weight.

' corporated.

' Ammonium perchlorate 1 about 600 Polyisobiityleiiez mol. wt.,

Ballistic Data at 70 F. and

non-viscous diluents is preferably not more than about 25 mm. Hg at 100C.

The amount of liquid fuel vehicle in the composition is critical onlyinsofar as an adequate amount must be present to provide a continuousmatrix in which the solid phase is dispersed. This will vary to someextent with the particular solids dispersed, their shape, and degree ofsubdivision, and can readily be determined by routine test formulation.The minimum amount of liquid required generally is about 8%, .usuallyabout 10% by portion of liquid fuel to dispersed solid can be employed,

' depending on the desired combustion properties, since the desiredcohesive, shape-retentive properities' can be obtained by adjusting theviscosity of the fluid matrix.

' The solid oxidizer can be any suitable, active oxidizing agent whichyields oxygen readily for combustion ofthe fuel and which is insolublein the liquid fuel vehicle. Suitable oxidizers include the inorganicoxidizing salts, such as ammonium, sodium, potassium and lithiumperchlorate or nitrate, metal peroxides such as barium per- The solidoxidizer should be finely 300 to 600 microns, to ensure stable, uniformdispersion of the oxidizer in the liquid fuel, so that it will notseparate or sediment despite lengthy storage periods, although somesomewhat'larger particles, e.g. up to about 1000 microns, can bemaintained in the viscous fuel matrix without separation. Optimumparticle size is to a considerable extent determined by the viscosity ofthe par- .ticularliquid matrix and can readily be determined withroutine testing by those skilled in the art. Although not essential, asize dispersion of the particles is often desir- Y able because of theimproved packing elfect obtained in terms of increased amounts of solidswhich can be in- Improved loading densities are obtained withoxidizer'particles so distributed in size that the minimum ratio of sizeof the smallest t the largest is b about 1:2 and preferably about 1:10.

The amount of solid oxidizer incorporated varies, of course, with theparticular kind and concentration of fuel components in the formulation,the particular oxidizer, and the specific requirements for a given use,in terms, for example, of required heat' release and rate of gasgeneration, and can readilybe computed by those skilled in the art. Theupper limit of oxidizer addition. is

set only by the requirement that it be dispersed in a continuous matrixof the liquid vehicle. Since the liquid vehicle can be loaded with ashigh as 80 to 92% of finelydivided solids, stoichiometn'c oxidizerlevels with respect to the inert liquid or inert liquid and metal fuelcomponents can generally be obtained where desired, with increasedlatitude in some cases being provided, if desired,

Beyond the requisite minimum any desired pro Table I by addition of anon-viscous, self-oxidant, viscosity-adjusting diluent. Asaforementioned, injsome applications, stoichiometric oxidation levelsmay not be neces sary or even desirable and the amount of oxidizer canbe correspondingly reduced, it being essential onlythat adequateoxidizer be present toiprovidefor active combustion oi the fuelcomponents and an adequate degree of gas generation for the particularuse.

Finely-divided, solid metal powders, such as Al, Mg, Zr, B, Be, Ti, andSi, can be introduced into the monopropellant compositions as anadditional fuel component along with the liquid fuel. Such metal powdersposses the advantages both of increasing density and improving Ingeneral, the metal Will constitute aminorfproportion by weight of thepropellant composition, maximum limits,

being set by the need to avoid granulation of the. mixture and anexcessive deficiency in amount of oxidizer.

Other additives which can be incorporated into the monopropellantcompositions include, for example, burn ing rate catalysts, such asammonium dichromate, copper chromite and ferric ferrocyanide; coolantsfor reducing the temperatures of the generated gases where necessary, asin the case of some turbine applications, such as monobasic ammoniumphosphate, barbituric acid and ammonium oxalate; and the like.

The heterogeneous monopropellants are prepared simply by mixing thecomponents in any siutable mixing apparatus. In addition'to theirsimplicity, manufacturing operations are relatively'non-hazardousbecause of the low sensitivity of the components. portion of the liquidfuel is a highly active compound, such as nitroglycerine, dilution withthe inert liquid polymer greatly reduces shockand impact-sensitivity.

Table I summarizes a variety of propellantformulations in which liquidpolyisobutylene of different molecular weights and viscosities wasemployed as theviscous liquid fuel matrix. Dibutyl phthalate and a lowviscostain of the compositions as a catalyst to increase burning rateand reduce pressure exponent, its marked efi'ectb'eing clearly shown bycomparison of #24 and 25 and #23 and 26. Ballistic data are given wherevavailable.

Composition (parts by #11 I #12. #13 #14 #15 #16 I weight) (6900 r.p.m.,2TH grind). Ammonium perchlorate (unground)' Ammonium perchlorate(14,000 r.p.rn. grind) Polyisobutylene, mol. wt.

1 5. 00 IPolyisobutylene, mol. wt., 7

Dibutyl phthalat 6. 25 Silicone oil, 5000p Aluminum 8 Copper chromite-Wetting agent O per 070 Burning rate (in./scc.)

Pressure exp 1 24 micron weight average size. 2 194 micron weightaverage size.

F. 5 Viscosity about 1,000,000 eentipoises at 100 F.

B 8 Micron weight average size.

Viscosity about-7000 centipoises at 100 F.

4 Viscosity about 300 centipoises at 3 51.4 micron Weight average size.

7 Viscosity about 500 centipoises at 100 The metal particles should,

Even where a Table II Composition (parts by weight) Polydimethylsiloxane1 Polyester 2 Ammonium perchlorate (6900 r.p.m. 2TH grind). Ammoniumperchlorate (unground) Aluminum (8 micron wt.-av.-s1ze)- Copper chromitc0 .1 Ballistic Data at and 1000 Burning rate (in./sec.) 1.10 0. 34Pressure exponent 0. .1 O. 35 Autoignition temperature, 280 265 1Viscosity 460 centipoiscs at 77 F.

3 Viscosity about 50,000 eentipoises at 77 16.

Although this invention has been described with reference toillustrative embodiments thereof, it will be apparent to those skilledin the art that the principles of this invention can be embodied inother forms but within the scope of the claims.

I claim:

1. In a heterogeneous monopropellant composition consisting essentiallyof finely-divided, solid, insoluble, inorganic oxidizer, dispersed in acontinuous, oxidizabie, organic fuel matrix, and which burns to formgaseous combustion products, said fuel matrix being a mobile liquidwhich forms at least about 8% by weight of said composition, andcomprises one or more organic liquid components, all of which containmolecularly-combined carbon and hydrogen and have a maximum vaporpressure of about 25 mm. Hg at 100 C., and at least one of which is aninert compound requiring an external oxidizer for combustion, saidinorganic oxidizer being present in amount sufficient to maintain activecombustion of the inert organic fuel compound, the improvement in whichsaid liquid fuel matrix has a minimum viscosity of about 400 centipoisesat 77 F., and consists essentially of a synthetic liquid organic polymerwhich has a minimum viscosity of about 400 centipoises at 77 F, issufficiently mobile to flow at ordinary temperatures, and does notfurther polymerize substantially in said monopropellan-t compositionduring storage, said monopropellant being an extrudable, thixotropiccomposition which requires a finite stress to produce flow, isindefinitely capable, after storage, of continuous flow at ambienttemperatures under a maximum shear stress at a Wall of about p.s.i., andhas a minimum tensile strength of about 0.01 p.s.i., said viscous liquidpolymer serving to impart thixotropic properties to the monopropellantcomposition and to hold the dispersed solids in stable dispersion.

2. The monopropellant composition of claim 1 in which the syntheticliquid organic polymer is selected from the group consisting ofhydrocarbon polymers, siloxanes, alky-l polyesters, acrylic andmethacrylic acid esters, polydiols, epoxy polymers and phenolicpolymers.

3. The monopropeilant composition of claim 1 in which the syntheticliquid organic polymer component comprises a mixture of synthetic liquidorganic polymers having different viscos-ities, the least viscouspolymer having a minimum viscosity of about 400 centipoises at 77 F.

4. The monopropellant composition of claim 1 in which the synth eticliquid organic polymer has a viscosity which is subst'an-tiaily higherthan about 400 centipoises at 77 'F., and higher than the desiredviscosity of the liquid fuel mixture, and is admixed w ith anoxidize-bio non-viscous onganic liquid fuel which has a viscositysubstantially less than 400 centipoises at 77 F, sid non-viscous liquidbeing present in an amount which reduces the viscosity of the liquidfuel to the desired viscosity, the minimum viscosity of the mixturebeing about 400 centipoises at 77 .F, and thereby providing a means forcontrollably adjusting the viscosity of the liquid fuel matrix.

5. The mono-propellant composition of claim l which contains, inaddition, a minor proportion by weight of a finely-divided metal fueldispersed the continuous matrix of the organic liquid fuel.

6. The monopropellant composition of claim 1 in which the minimumtensile strength is about 0.03 p.s.i.

7. The monopropellant composition of claim 6 in which the syntheticliquid onganic polymer is selected from the group consisting ofhydrocarbon polymers, siloxanes, alkyd polyesters, acrylic andmethacrylic acid esters, polydiois, epoxy polymers and phenolicpolymers.

8. The monopropeilant composition of claim 6 in which the syntheticiiquid organic polymer component comprises a m" e of synthetic liquidorganic polymers having different viscosities, the least viscous polymerhaving a n1inimum viscosity of about 400' centipoises at 77 F.

9. The monopropellent composition of claim 6 in which the synthe cliquid organic polymer has a viscosity which ly higher than about 4-00centipoises at 77 F., and higher than the desired viscosity of theliquid fuel mixture, and is admixed with an oxidizable non-viscousorganic liquid fuel which has a viscosity substantially less than 400centipoises at 77 F., said non-viscous liquid being present in an amountwhich reduces the viscosity of the liquid fuel to the desired viscosity,the minimum viscosity of the mixture being about :00 centipoises at 77F, and thereby providing a means for control'lably adjusting theviscosity of the liquid fuel matrix.

10. The monopropeilent composition of claim 9 in which the syntheticliquid polymer is an inert compound which requires an external oxidizerfor combustion, and the non-viscous organic fuel component is an activecompound which contains combined oxygen avaiia-ble for oxidiz at'ion ofother molecularly'combined components of said active compound to formgaseous combustion products.

11. The monopropellant composition of claim 6 in which the liquid fuelmatrix and the synthetic liquid organic polymer component have minimumviscosities of about 1500 cen-tipoises at 77 F.

12. The monopropel-lent composition of claim 7 in which the liquid fuelmatrix and the synthetic liquid organic polymer component have minimumviscosities of about 1500 centipoises at 77 F.

13. The inonopropelient composition of claim 8 in which the liquid fuelmatrix and the mixture of liquid organic polymers have minimumviscosities of about 1500 centipoisee at 77 F.

14. The monopropelient com-position of claim 9 in which the liquidorganic polymer has a viscosity substantially higher than about 1500centipoises at 77 F. and the non-viscous organic liquid is present in anamount which reduces the viscosity of the liquid fuel matrix to aminimum of about 1500 centipoises at 77 F.

15. The monopropellent composition of claim 10 in which the liquidorganic polymer has a viscosity substantially higher than about 1500centipoises at 77 F. and the non-viscous organic liquid is present in anamount which reduces the viscosity of the iiqu-id fuel matrix to aminimum of about 1500 centipoi-ses at 77 F.

.16. The monopropellent composition of claim 7 in which the syntheticliquid organic polymer is a hydrocarbon polymer.

17. The monopropellen-t composition of claim 12 in which the syntheticliquid organic polymer is a hydrocarbon polymer.

18. The monopropellent composition of claim 17 in which the hydrocarbonpolymer is liquid polyiso butylene.

19. The monopropellent composition of claim 18 in which the solidoxidizer is'finelyaiivided ammonium perchlorate.

20. The monopropellent composition of claim 12 in which the syntheticliquid organic polymer is a polyester.

'21. The monopropellent composition of claim 12 in which rthe syntheticliquid organic polymer is a siloxane.

22. The monop ropellent composition of claim 6 which contains, inaddition, a minor proportion by weight of a finely-divided metal fueldispersed in the continuous matrix lot" the organic iiquid fuel. 7 v

23. The monop-ropellent composition of claim 7 which contains, inaddition, a minor proportion by weight of a finely-divided metal fueldispersed in the continuous matrix esters, polydiols, epoxy polymers andphenolic polymers. 15

25. The monopropellent composition of claim 24 which contains, inaddition, a minor proportion by Weight of V finely-divided metal fueldispersed in the continuous matrix of the organic liquid fuel. r

26. The monopropellent composition of .olainr 6 in which the solidoxidizer comprises particles distributed in size such that size ratio ofthe largest and the smallest particles is about 2 to 1.

27. The monopropellent composition of claim 7 in 10 which the solidoxidizer comprises particles distributed in size such that minimum sizeratio of the largest and the smallest particles is about 2 to 1.

No references cited.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,113,894 December 10, 1963 Joe M. Burton It is hereby certified thaterror appears in the above numbered patent requiring correction and thatthe said Letters Patent should read as corrected below.

Column 3, lines 20 and 21, for "viscose" read viscous column 4, line 14,for "triethyene" read triethylene column 6, line 35, for "siutable" readsuitable columns 5 and 6, Table I, footnote 4, for "300" read 3000Signed and sealed this 28th day of July 1964.

(SEAL) Attest:

ESTON G. JOHNSON EDWARD J BRENNER Attesting Officer Commissioner ofPatents

1. IN A HETEROGENEOUS MONOPROPELLANT COMPOSITION CONSISTING ESSENTIALLY,OF FINELY-DIVIDED, SOLID, INSOLUBLE, INORGANIC OXIDIZER, DISPERSED IN ACONTINUOUS, OXIDIZABLE, ORGANIC FUEL MATRIX, AND WHICH BURNS TO FORMGASEOUS COMBUSTION PRODUCTS, SAID FUEL MATRIX BEING A MOBILE LIQUIDWHICH FORMS AT LEAST ABOUT 8% BY WEIGHT OF SAID COMPOSITION, ANDCOMPRISES ONE OR MORE ORGANIC LIQUID COMPONENTS, ALL OF WHICH CONTAINMOLECULARLY-COMBINED CARBON AND HYDROGEN AND HAVE A MAXIMUM VAPORPRESSURE OF ABOUT 25 MM. HG AT 100*C., AND AT LEAST ONE OF WHICH IS ANINERT COMPOUND REQUIRING AN EXTERNAL OXIDIZER FOR COMBUSTION, SAIDINORGANIC OXIDIZER BEING PRESENT IN AMOUNT SUFFICIENT TO MAINTAIN ACTIVECOMBUSTION OF THE INERT ORGANIC FUEL COMPOUND, THE IMPROVEMENT IN WHICHSAID LIQUID FUEL MATRIX HAS A MINIMUM VISCOSITY OF ABOUT 400 CENTIPOISESAT 77*F., AND CONSISTS ESSENTIALLY OF A SYNTHETIC LIQUID ORGANIC POLYMERWHICH HAS A MINIMUM VISCOSITY OF ABOUT 400 CENTIPOISES AT 77*F., ISSUFFIENTLY MOBILE TO FLOW AT ORDINARY TEMPERATURES, AND DOES NOT FURTHERPOLYMERIZE SUBSTANTIALLY IN SAID MONOPROPELLANT COMPOSITION DURINGSTORAGE, SAID MONOPROPELLANT BEING AN EXTRUDABLE, THIXOTROPICCOMPOSITION WHICH REQUIRES A FINITE STRESS TO PRODUCE FLOW, ISINDEFINITELY CAPABLE, AFTER STORAGE, OF CONTINUOUS FLOW AT AMBIENTTEMPERATURES UNDER A MAXIMUM SHEAR STRESS AT A WALL OF ABOUT 10 P.S.I.,AND HAS A MINIMUM TENSILE STRENGTH OF ABOUT 0.01 P.S.I., SAID VISCOUSLIQUID POLYMER SERVING TO IMPART THIXOTROPIC PROPERTIES TO THEMONOPROPELLANT COMPOSITION AND TO HOLD THE DISPERSED SOLIDS IN STABLEDISPERSION.